Methods and apparatus for transparent tone-in-band transmitter, receiver and system processing
CA 2012917 C · Owner: British Technology Group Limited · Inventors: Bateman, Andrew
Overview
Its claims, description and drawings are in the Canadian Patents Database.
Open the CIPO recordAbstract From the Canadian patent
In deriving a control signal for recombining the parts of the spectrum separated by a frequency notch in transparent tone-in-band signals, cross-correlation products give rise to undesirable frequency and phase fitter. In a receiver which overcomes this problem an input signal E containing the notch is passed to two first mixers and then portions corresponding to the lower and upper portions of the input spectrum are selected by two mirror filters before being translated in frequency by two second mixers to a final output band in which the notch is eliminated. Two selection filters select parts of the spectra at the outputs of the first mixers which correspond to an overlap region of the …
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Listed from its CIPO record in Patent Yard's archive of Canadian patents past their term. Its claims, description and drawings are in the CIPO record and on Google Patents, and the Claude kit works from them.
Why it's free to use
- Filed March 23, 1990 and granted March 28, 2000. A Canadian patent filed from October 1, 1989 lasts 20 years from filing, so its term ended March 23, 2010.
- A certificate of supplementary protection adds at most two years for a drug, so even that would have ended by March 23, 2012.
- We check Canadian rights only. A patent in its family in another country could still be in force: check its family on Google Patents.
Timeline
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Official CIPO records
Everything on this page comes from the CIPO record linked above. Contains information licensed under the Open Government Licence – Canada.